Server-Side Request Forgery (SSRF) Affecting mcp-atlassian package, versions <0.23.0-r0


Severity

Recommended
0.0
critical
0
10

Snyk's Security Team recommends NVD's CVSS assessment. Learn more

Threat Intelligence

EPSS
1.37% (71st percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-CHAINGUARDLATEST-MCPATLASSIAN-18015559
  • published19 Jul 2026
  • disclosed2 Apr 2026

Introduced: 2 Apr 2026

CVE-2026-32871  (opens in a new tab)
CWE-918  (opens in a new tab)

How to fix?

Upgrade Chainguard mcp-atlassian to version 0.23.0-r0 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream mcp-atlassian package and not the mcp-atlassian package as distributed by Chainguard. See How to fix? for Chainguard relevant fixed versions and status.

FastMCP is a Pythonic way to build MCP servers and clients. Prior to version 3.2.0, the OpenAPIProvider in FastMCP exposes internal APIs to MCP clients by parsing OpenAPI specifications. The RequestDirector class is responsible for constructing HTTP requests to the backend service. A vulnerability exists in the _build_url() method. When an OpenAPI operation defines path parameters (e.g., /api/v1/users/{user_id}), the system directly substitutes parameter values into the URL template string without URL-encoding. Subsequently, urllib.parse.urljoin() resolves the final URL. Since urljoin() interprets ../ sequences as directory traversal, an attacker controlling a path parameter can perform path traversal attacks to escape the intended API prefix and access arbitrary backend endpoints. This results in authenticated SSRF, as requests are sent with the authorization headers configured in the MCP provider. This issue has been patched in version 3.2.0.

CVSS Base Scores

version 3.1